fix safari cannot play ts file problem.

[suzp1984]

Bug:

MacOS safari can't play TS file.

steps to reproduce

1. clone this project https://github.com/xqq/mpegts.js, and build the project, (check the README).
   npm install; npm install -g webpack-cli; npm run build;
2. run the webpack serve: npm run serve;
3. access page http://localhost:8080/arib.html in safari;
4. find/generate a test.ts file with audio codec as opus;
   e.g. by ffmpeg: ffmpeg -i [file].[aac|opus] -acodec opus test.ts
5. start a static web server in the folder of test.ts,
   e.g. by this python script: https://gist.github.com/mkows/cd2122f427ea722bf41aa169ef762001
python server-cors.py 9921
6. in page http://localhost:8080/arib.html, input Stream URL as: http://127.0.0.1:9921/test.ts, deselect isLive & withCredentials & liveSync checkbox. then click Load button.
7. the opus audio can not play in safari.

Root Cause

the Safari web browser don't support MIME audio/mp4;codecs=opus, but support audio/mp4;codecs=Opus.

In side safari web dev tools, go to Console tab. Input MediaSource.isTypeSupported('audio/mp4;codecs=opus') and MediaSource.isTypeSupported('audio/mp4;codecs=Opus') to verify.

[xqq]

Thank you!